Animals commonly suffer joint injuries of the limbs. These injuries frequently require surgery and/or use of orthoses such as braces or splints to support and stabilize the joint. Braces and splints provide immobilization of the limb, by resisting flexion and extension of the joint, and also provide stabilization by maintaining proper alignment of the joint in relation to the rest of the limb while providing support to the joint.
Braces and splints are used to provide support and stabilization to an animal's fore and/or rear limbs due to injury or surgery. A common joint injury seen in animals, often requiring the use of a brace or splint, is a torn ligament, particularly of the cranial cruciate ligament (CCL). The CCL is located in the knee or stifle joint of an animal's rear leg and, in canines, a CCL injury is the most common torn ligament injury. It is estimated that, per year, 1.2 million dogs undergo surgery to repair the CCL at a cost of approximately $1.3 billion. It is further estimated that of the 73 million dogs in the United States, 37% of large breed dogs and 45% of small breed dogs rupture their CCL.
Various types of animal orthoses are currently available and run the gamut from completely immobilizing the limb to allowing limited limb mobility. Braces and splints that immobilize the limb are generally one continuous structure and are universally sized to fit animals within a certain size range. The universal devices are generally not modified to fit an individual animal or can only be slightly modified and are generally inexpensive.
Braces that allow a fuller range of motion are more expensive and generally consist of two or more pieces that are joined to form a hinge or joined by a hinge. Hinged braces can be universally sized or are custom made and fitted. Hinged braces are generally bulky, cumbersome, and heavy. The upper portion is generally constructed of a flexible plastic or rubber material that partially surrounds the upper limb and is held in place with at least one hook and loop closure (e.g. VELCRO® brand look and loop closures) or straps. The bottom portion is normally connected to the upper portion with a hinge mechanism. The bottom portion is held to the lower limb using at least one hook and loop closure (e.g. VELCRO® brand hook and loop closures) or straps. In addition, the hinged braces can have stabilizing bars formed into the brace.
A common problem with the universal braces and splints, whether hinged or the one-piece construction, is that the brace or splint is not properly fitted resulting in either too much compression of the limb or too much float within the brace or splint. Another common problem is that the lineal proportions can also be out of scale in comparison to the animals limb so that the brace or splint is either too long or too short.
Custom made and fitted braces and splints normally require casting, molding, and fitting activities over a period of weeks requiring multiple trips to the veterinarian. One example of a custom fitted brace is manufactured by Ace Ortho Solutions. This jointed brace is custom fitted using a casting, molding, and fitting process which can take at least two weeks. A casting is made, by a veterinarian, of the animals limb and is mailed to an off-site laboratory. The brace is shaped from co-polymer plastic based on the casting of the animals limb and shipped back to the veterinarian. A separate unattached piece of neoprene is provided with the brace that the veterinarian must correctly trim for proper fitting. The neoprene is then tightly wrapped around the limb. The brace is placed over the neoprene with the idea that the neoprene prevents the brace from slipping. Strips of a hook and loop closure (e.g. VELCRO® brand and loop closures) are then tightly secured around the brace to compress the brace and hold it securely to the animals limb.
While custom made braces and splints address some of the fit problems presented by universal braces and splints, the delay between casting and fitting results in a period of time in which the animal can further injure itself or requires the added expense and inconvenience of temporary use of an alternate brace.
Another problem with existing animal limb braces and splints is the propensity for the brace or splint to slip or move. Various efforts have been made to solve this problem. Some braces and splints come equipped with an elaborate harness system. Others brace or splint beyond the affected area in an attempt to use other areas of the limb or body to hold the brace in place. Some use a “non-slip” material between the animals limb and the brace or splint. Some just accept the slippage as a matter of course.
Another problem with existing animal limb braces and splints is that the devices are normally made or designed to treat or support only one joint or one localized limb area when the entirety of the limb may need treatment or support. This then results in using various braces and/or splints that were not designed to be used in conjunction with each other and the treatment or support can be ineffective.
Another problem with existing animal limb braces and splints is the internal portion of the brace or splint that is adjacent the leg becomes dirty and riddled with bacteria thus presenting hygienic issues and in some instances, providing a vehicle for the introduction of infection to an incision area. Additionally, if the padding is not fitted correctly, the circulation of the limb is affected severely damaging the limb or paw.
Generally, existing animal limb braces and splints utilize strips of a hook and loop Closure (e.g. VELCRO® brand look and loop closures) or straps as the tightening and/or attachment method. This allows the brace or splint to be adjusted by pulling the strip/strap tighter or loosening it. However, a problem with this method is that it provides compression of the brace or splint only at the strip/strap locations and causes a pressure point where the strip/strap contacts the animals limb, resulting in inconsistent, uneven or undue pressure.
While significant advances have been made for human knee braces, it would not be suitable to modify a human knee brace to fit the stifle joint of an animal. The biomechanical forces of a human knee are much different than those of an animal. For example, the stance of the canine knee is different than the stance of the human knee. Humans stand upright, with their femur directly on top of their tibia, having a joint angle of 180°. Dogs stand with an angle of 135°. Thus, every time that a dog stands, the bone alignment is dependent upon an intact CCL to hold the bones in place in the stifle (knee) joint. Additionally, the actual structural dimensions of animal limbs vary significantly from that of humans. For example, the cross section of the upper thigh area of a human leg is substantially round while the cross section of the upper thigh area of a canine's rear leg is substantially oval. Thus, the forces acting on the leg from the contact points of the brace can be quite different.
There is also an overall variability in animal scale size among varying animal species and breeds that is significantly greater in animals than in humans. Thus, there is a greater variability in the circumference and length of animal limbs versus human legs.
In view of the shortcomings of known animal limb braces and splints, there is a demand for an orthopedic animal brace or splint which is simple to employ but capable of exerting distributed compression forces against the animal to effectively treat and stabilize the weakened limb, is customizable in size, and provides sufficient anatomical support capable of servicing a wide variety of anatomical contours and treatment levels.